Wire rope center testing



Dec. 9, 1941. J J. BURKE ETAL WIRE ROPE CENTER TESTING 2 Sheets-Sheet lFiled April 10; 1939 Jay/v -/0PH BURKE my 50W 5?: 645 544.

Patented Dec. 9, 1941 2,265,142 WIRE ROPE CENTER TESTING John JosephBurke and Edwin Ernest Caspell, New Haven, Conn., assignors to TheAmerican Steel and Wire Company of New Jersey, a corporation of NewJersey Application April 10, 1939, Serial No. 267,106

4 Claims.

This invention relates to wire rope centers or cores and is particularlyconcerned with testing these centers or cores to determine how they willact in a rope laying machine and when placed in service as part of afinished rope.

A specific example oithe invention is illustrated in the accompanyingdrawings, in which:

Figure 1 is an elevation;

Figures 2 and 3 are enlargements taken from Fi ure 1';

Figure 4 is a sectional enlargement taken from Figure 3; and,

Figure 5 is a modification.

More specifically, these drawings show a bench I mounting a chuck 2 anda cam type jaw 3, these two units being adapted to engage the oppositeends of a rope center specimen C whose characteristics are to bedetermined.

The chuck 2 reciprocatively rides a guide 4 and connects with a screw 5reciprocated by a nutgear l5 turned by motor I through a gear reductionunit 8. Operation -of the motor I reciprocates the screw 5 which isfixed against rotation, and so reciprocates chuck 2.

It is possible to tension the center by means of the above arrangement,the jaw I reciprocatively riding a guide 9 and connecting through a barI!) with a tension indicating scale H, the latter applying the necessaryreaction to the Jaw 3 by way of the connecting bar Ill, so that thecenter specimen may be tensioned. At the same time, the scale indicatesthe tension applied the specimen. i

Connection of the screw 5 with the chuck 2 is by way of a frame l2, thechuck being rotatively carried by this frame, its rotation beingefiected by a worm gear l3 fixed to its rotative mounting shaft andoperated by a worm l4 powered'by a handwheel I5. Thenumber of rotationsor turns given the specimen is indicated by a counter l6 connected withthe rotative shaft of the chuck by way of gearing ll.

Fibrous rope centers are made under tension by cordage manufacturerswith a certain number of crowns per unit of length. When a specimen iscut, the tension on this specimen is released manufacturer.

A circular frame I8 is fixed to the top of the bench lintermediatethechuck2and jaw 3 so that the specimen passes through thisframe. A plurality of hydraulic cylinders 19 are positioned by thisframe I B so as to point radially toward the specimen, pistons 20operating in these cylinders l9 and the latter being interconnected andconnected with a suitable source of fluid under pressure, the pressureapplied the cylinders being indicated by a pressure gage 2|.

Each of the above pistons 20 removably carries an element 22 at itsouter end, this element being in the form of a round bar having itsouter surface contoured to simulate at least approximately the contour.of a, rope strand. There should be one of these elements 22 for each ofthe strands of the rope for which the center, the specimen of which isunder test, is to be used, the drawing illustrating six cylinders,pistons and elements because the six-strand rope is a common rope. Also,the diameters of the elements 22 should be the-same as these ropestrands, and the contours of these elements should, preferably, exactlysimulate the contours of these strands. In actual practice verysatisfactory results are obtained when the elements 22 are simplysmooth, round bars havingthe same diameters as the rope strands to belaid over the center, the specimen of which is under test. In all cases,the elements 22 should have sufficient lengths to act as do rope strandsclosing on a center in a rope laying machine.

To use the testing apparatus here described, the specimen is fixed inthe chuck 2 and jaw j, the motor 1 being used to apply tension to thespecimen and the handwheel l5 being operated to twist the specimen. Thescale ll provides an indication of the tension applied the specimenwhile the number of twists it is given are shown by the counter l6.

Fluid is then applied to the various cylinders l9, this forcing theelements 22 radially against the rope to simulate the action of ropestrands closing on a center. The pressure required to bring the elementsinto tangency may be used, for instance, as an indication of what thedie pressure must be when actual rope strands are closed on the centerin the die of a rope laying machine.

Since the elements 22 are straight, instead of helical, it is necessaryto apply a correction factor in calculating the results of the test.This factor is based upon the angle of lay of the actual rope, thesecant of the angle of lay of the rope strands about the center of thelaying machine being known.

Many rope laying machines use a two-Part rope strand closing die, and insuch instances the application of equal pressure to all the elements 22may not provide an accurate indication of what will take place in'themachine. The modification, therefore, shows an arrangement using onlytwo of the cylinders l9 and pistons 20, each of the latter mounting anelement providing three interconnected round bars, this arrangementsimulating the action of a two-part die. In case a four-part die is usedby the rope laying machine, there should be four cylinders and pistons,each provided with elements simulating the rope strands handled by thevarious die parts. That is to say, pressure may be applied the elementsin the same manner it is applied in the rope laying machine.

It js to be understood that a wire rope conventionally comprises aplurality of helical strands each made up of a plurality of intertwistedwires, the strands being laid on a center or core which radiallysupports the strands to hold them in their proper relation when the ropeis tensioned. Such a center or core is usually made up of hemp fibers,it having somewhat the appearance of hemp rope but being speciallydesigned to enable it to properly perform its intended function.

- Sometimes the center ,or core is made of intertwisted wires, .or itmay be made of rubber or the.

like. In all instances the center or core is a very important part ofthe rope into which it is incorporated, since if it fails to properlysupport the rope strands the latter lose their relative positions sothat tensile stresses do not properly distribute through the strandswhereby one or another of the latter receives more than its share of theload, this causing the rope to fracture under a smaller load than thatcalculated as the ultimate load the rope should carry safely.

At the present time, there is no accurate means for predetermining theaction of an untried center except by incorporating it in anexperimental rope made in a rope laying machine. To be a trulyrepresentative test, this requires the manufacture of a considerablelength of rope, this involving an expensive outlay of material and thestoppage of production insofar as is concerned the machine used to makethe test length.

The use of the present invention permits an experimental determinationof the pressure that must be applied to close the rope strands overa'newly designed center. It is possible to vary the speed with which thevarious elements are powered to radially press them against thespecimen, this enabling the test to give at least some indication ofwhat will occur when the rope strands are dynamically pressed againstthe center of the rope layingmachine.

Furthermore, the invention permits a determination of the'eiiects ofvaryingthe tension on the center as well as varying its twist. It is tobe understood that the length of the specimen should be sufficient to betruly representative of,

the center and, as previously indicated. that the lengths of the variouselements 22 should be suiiicient to be truly representative of whatoccurs when the actual rope strands are laid in place.

As previously mentioned, the elements 22 are removably carried by thepistons 20, and there should be a supply of theseelements of varyingdiameters, numbers and groupings to permit the machine to be used totest centers used in the various types of rope constructions.

' are largely a matter of choice, the only requirement being that theyenable the parallel arrangement of the various elements desirable toproduce consistent results.

Various additions to what has been disclosed, which might make for moreconvenient operation. will suggest themselves to the experienced, suchas, for instance, the guides 23 which are illustrated by the drawingsbut not previously described, these guides serving to indicate a givenlength of the center specimen, this being necessary to determine thenumber of crowns obtained per unit of length of the specimen by twistingand tensioning the latter, amounts which can be determined by the scaleII and counter l6. Although the various elements are shown as beingpressed against the specimen by hydraulic means. it is possible to usemechanical means provided with suitable pressure indicating instruments.

We claim:

1. A wire rope center testing apparatus including the combination of aplurality of elongated elements, means for positioning said elements inlaterally opposed relation so they form a substantially cylindricalgroup with at least some of said elements movable radially of saidgroup, means for forcing the movable ones of "said elements radiallyinwardly respecting said group and means for indicating the forceexerted by the second named means, said combination including means forpositioning a sample of the center to be tested longitudinally throughthe inside of said group of said elements. the last named means beingadapted to variably tension said sample, and means for indicating thetension applied said sample by said last named means.

2. A wire rope center testing apparatus including the combination of aplurality of elongated elements, means for positioning said elements inlaterally opposed relation so they form a substantially cylindricalgroup with at least some of said elements movable radially of saidgroup, means for forcing the movable ones of said elements radiallyinwardly respecting said group and means for indicating the forceexerted by the second named means, said combination including means forpositioning a sample of the center to be tested longitudinally-throughthe inside of said group of said elements, the last named means beingadapted to variably tension said sample, and means for indicating thetension applied said sample by said last named means, the latter alsobeing adapted to variably apply torque to said sample and means beingprovided for indicating the torque applied by said last named means.

3. Strand testing equipment including the combination of means forlongitudinally positioning and tensioning a sample of the strand to betested, laterally opposed and respective laterally movable elementspositioned longitudinally on opposite sides of said sample positioned bysaid means, means for forcing said elements together to laterallycompress said sample therebetween, means for indicating the tensionapplied said sample by the first named means and means for indicatingthe lateral compression applied said sample by said elements.

4. Strand testing equipment including the combination of means forlonsitudinally positioninz and tensioning a sample of the strand 2 to betested, laterally oppoud and respective laterally movable elementspositioned l0ngitudinally on opposite sides of said sample positioned bysaid means, means for forcing said elements together to laterallycompress said sample therebetween, means 101' indicating the tensionapplied said sample by the first named .a

' means andmeans tor indicatina the lateral compression applied saidsample by said elements,

saidtirst named means being adapted to apply torque to said sample andsaid combination insaid sample by said first named means.

eluding means for indicating the torque applied,

" JOHN JOSEPH BURKE. V l mar CASPELL.

